TOKYO (AFP) - A volcano in southwestern Japan has erupted, flinging large rocks hundreds of metres from the crater and prompting the meteorological agency to raise its alert level, Kyodo news agency reported early on Wednesday (March 31).

There were no immediate reports of injuries after the eruption of Mount Otake in Kagoshima prefecture, according to Kyodo.

The report said the Japan Meteorological Agency had raised its alert level to a three on a scale of five, meaning that people should not approach the crater.

A first eruption reportedly took place just after 10pm on Tuesday, with a second near 3am on Wednesday.

Kyodo said large rocks were projected "nearly 1km" from the crater, and warned that they could potentially reach a 2km radius.

Japan, with scores of active volcanoes, sits on the so-called Pacific "Ring of Fire", where a large proportion of the world's earthquakes and volcanic eruptions are recorded.